To dissect out the subclasses of lymphoid cells responsible for effecting anti-tumor immunity. To see what role activity of each of the subclasses dissected plays in any given immune response and then to manipulate either the antigenic stimulus or the ratios of the various of subclasses of lymphocytes to see how these manipulations effect the anti-tumor immune response. To determine the relevant antigens on tumor cells which activate the different subclasses of lymphocytes; in particular, suppressor, helper and killer T cells. To isolate and characterize factors which transmit signals between the various subclasses of cells. To identify, isolate and characterize the receptors on lymphoid cells which receive the signals (including the signal of the stimulating antigen). To alter and modify antigens in a meaningful way so that the response of the various subclasses of lymphocytes is distinctly altered and to determine how these alterations affect the overall anti-tumor immune response. Part 1 of 8.